Surface reaction process at epitaxial growth of 3C-SiC on Si(001) using organosilicon compounds

本项目的目标是了解以有机硅化合物为源材料在Si（001）衬底上外延生长3C-SiC的反应过程，以实现具有优异性能的SiC的低温外延生长。用反射高分辨原位观察了二甲基硅烷（DMS）或单甲基硅烷（MMS）在Si（2x 1）表面的初始反应过程。能量电子衍射（RHEED）和扫描隧道显微镜（STM）：在SiC成核前的保温时间内，在RHEED图上出现的Si c（4 × 4）结构表面，STM测量观察到Si（2 × 1）和Si c（4 × 4）结构。从通过线形测量对两种结构的晶格常数的评估来看，c（4x 4）畴收缩，Si（2x 1）畴扩展。SiC岛不是沿衬底表面的原子台阶沿着成核，而是在台阶上成核。此外，SiC岛生长沿着<100>方位从AFM测量。这个方向与碳原子扩散到c（4x 4）亚表面层的位置一致。根据这些结果，可以认为SiC岛是在c（4x 4）区域上形成的。2003年，使用四极质谱仪鉴定了从反应表面脱附的自由基和分子。甲基和甲硅烷基几乎没有检测到，氢分子只在MMS（DMS）和Si（2x 1）表面之间的反应过程中检测到。从这些结果，甲基和甲硅烷基基团不从表面解吸，但分解成C和Si原子。在c（4x 4）结构的形成过程中，C原子扩散到衬底中，Si原子补偿二聚体空位，两种原子在薄膜生长过程中都被引入到SiC岛中。从使用质谱仪的程序升温脱附光谱，证实了在c（4x 4）表面上Si双占据二聚体（DOD）的背键中Si-C键的形成。

The objective of this project is to understand the reaction processes during the epitaxial growth of 3C-SiC on Si(001) substrates using organosilicon compounds as source materials in order to realize the low temperature epitaxial growth of SiC with excellent properties.In 2002, the initial reaction process of dimethylsilane(DMS) or monomechylsilane(MMS) on Si (2x1) surface was observed in-situ using reflection high-energy electron diffraction(RHEED) and scanning tunneling microscopy(STM) : On the surface of Si c(4x4) structure, which appears in RHEED pattern during incubation time before SiC nucleation, both Si(2x1) and Si c(4x4) structures were observed by STM measurement. From the evaluation of the lattice constant for the both structures by lineprofile measurement, the c(4x4) domain was contracted and the Si(2x1) domain was expanded. SiC islands were not nucleated along atomic steps of the substrate surface but on the terrace. In addition, the SiC islands were grown along <100> azimuth from AFM measurement. This direction agrees with that the positions of carbon atoms diffused into subsurface layer of c(4x4). From these results, it was considered that the SiC islands were formed on the c(4x4) domain.In 2003, radicals and molecules desorbed from the reaction surface were identified using a quadrupole mass spectrometer. Methyl and silyl groups were hardly detected, and hydrogen molecules were only detected during the reaction between MMS(DMS) and Si(2x1) surface. From these results, methyl and silyl groups do not desorb from the surface but decompose into C and Si atoms. The C atoms diffuse into the substrate and the Si atoms compensate dimer vacancies during the formation of c(4x4) structure, and both atoms are incorporated into SiC islands during film growth. From temperature-programmed desorption spectra using the mass spectrometer, the formation of Si-C bonds in the back bonds of Si double occupied dimers(DOD) was confirmed on the c(4x4) surface.